I hope this the place for this kind of question.
I was wondering if there is a way to do all the nitrations that need 100% HNO3 with only 70% on (i gess with less product)?
I heard of some synthesis used some material that boil at 60-70 degrees and that we dont need to be afraid from the nitration go mad and to be very
exotermic.

Also why some material need more than one nitration? I mean why don't just put alot of extra acids and it will make all the nitrations ?

100% is needed to get the NO2 attached to you to-be-nitrated molecule, that's why sulfuric acid is often added, as water scavenger.

Some materials (like TNT) do need more than one nitration, because the nitration is at differend temps, and it saves acid. If diluted acid is
discarded, less new acid is needed to bring the conc. back to a good %.
For some nitrations, a low % of HNO3 can be used for the first, and a high % for the last nitration, so it is more economical.

See the TNT thread for more info.

Never argue with idiots, they drag you down their level and beat you with experience.